FIGS. 5 to 7 show a conventional built-in clamp 101 which serves for connecting two tubes 102, 103 of a motor vehicle heat exchanger. One of the tubes 102 is provided at its end with a first flange 104. The other second tube 103, introduced slightly into the first tube 102, is provided, somewhat spaced apart from its end, with a periphery bead which forms a second flange 105 and which has a smaller outside diameter than the first flange 104. The clamp 101 is a stamped sheet-metal bent part which is designed symmetrically. The clamp 101 has a plurality of bent-round tabs 106 and two slots 107, running in the longitudinal direction of the clamp 101, in the end region 108 of the clamp 101, for positioning the clamp 101 and for pressing the two tubes 102, 103 together. To simplify assembly, the clamp 101 is provided in each case in the end region 108 with an introduction slope 109. Furthermore, all the edges are rounded for easier handling. A clamp of this type can be handled easily, but still leaves much to be desired with regard to misuse, such as the clamp being inadvertently pulled off.